Journalists try to talk to a North Korean official (in pink) at the morgue at Kuala Lumpur General Hospital

KILLING WITH CHEMISTRY

From the courtiers of Ancient Greece to Soviet spies and maybe now North Korean agents, poison has a long history as a weapon of murder, favoured by assassins for its stealthy delivery of the fatal blow. A would-be poisoner can choose from a catalogue of deadly chemicals, some of which are relatively easy to obtain. Ricin – naturally occurring in castor oil plant seeds – and thallium (rat poison) are notorious for their murderous properties. Arsenic delivers a slow and miserable death, while strychnine induces extreme body spasms as the victim’s respiratory system collapses. But “cyanide is the fastest killer and the easiest to detect, its pathology appears all over the body,” said Porntip Rojanasunan a forensic expert and adviser to Thailand’s Justice Ministry. She said the victim’s “bright red blood” in post-mortem is the telltale sign of a potential cyanide poisoning. Other chemicals such as potassium can cause “an extreme heart arrhythmia.. and can lead to a heart attack very quickly.” Slow-acting poisons may allow assailants to slink away from the crime scene undetected. But chemical compounds are not easy to store or handle and many carry a giveaway residue, smell or colour that makes them hard to conceal, Porntip added.

WAS DEATH A WARNING FROM ANOTHER FOREIGN POWER?

Analyst Tristan Webb told NK News that the killing may have been committed by another nation to scare regime leadership in Pyongyang.

Analyst Tristan Webb told NK News that the killing may have been committed by another nation to scare regime leadership in Pyongyang.

He said: “Several countries (not only the DPRK) have regrettably shown a willingness to assassinate individuals (a flagrant violation of international law) and it is conceivable that a country hostile to the DPRK chose to assassinate Kim Jong Nam as a member of the DPRK dynastic family in order to inspire fear within the DPRK leadership of further attacks.

“It is also conceivable that no government organs of any country were involved, and that the killing was purely related to the personal affairs of Kim Jong Nam.”

A police officer earlier told the Telegraph that the women may be Vietnamese and still in Malaysia.

Ahmat said: “While waiting for the flight, a woman came from behind and covered his face with a cloth laced with a liquid.

“Following this, the man was seen struggling for help and managed to obtain the assistance of a KLIA [Kuala Lumpur International Airport] receptionist as his eyes suffered burns as a result of the liquid.

“Moments later, he was sent to the Putrajaya Hospital where he was confirmed dead.”

Selangor police chief Datuk Abdul Samah Mat added: “Jong-nam experienced eye irritation then sought assistance at the airport before being sent to Putrajaya Hospital and was pronounced dead on the way.”

WHERE IS KIM'S SON?

Mystery surrounds the wherabouts of Kim Jong-nam's 21-year-old son Kim Han Sol. The youngster was born in Pyongyang in 1995 and moved to Macau with his father when he fell foul of the regime in the early 2000s. In a rare TV interview with Finnish broadcaster YLE in 2012, he spoke of his hope that the two Koreas would one day be reunited. He said: "I have always dreamed one day I will go back and make things better, make it easier for all the people there." Media reports say he is studying at France's prestigious Paris Institute of Political Studies in Paris.

Mark Tokola, vice president at the Korea Economic Institute in Washington, said it would be surprising if Kim Jong-nam was not killed on the orders of his brother, given that North Korean agents have reportedly tried to assassinate Kim Jong-nam in the past.

"It seems probable that the motivation for the murder was a continuing sense of paranoia on the part of Kim Jong-un, which may be a well-placed paranoia," Tokola said.

Although there was scant evidence that Kim Jong-nam was plotting against the North Korean leader, he provided an alternative for North Koreans who would want to depose his brother.

Kim Jong-un has had numerous political opponents murdered since taking power

There has long been speculation that China has been protecting Kim Jong-nam as a potential future North Korean leader if anything happened to Kim Jong-un.

He went into hiding in Malaysia after the execution of his uncle Jang Song-thaek in 2014.

He is the son of Song Hye-rim, an actress believed to have been a mistress of Kim Jong-il, who reportedly died in Moscow in 2012.

A source claimed a North Korean agent tried to assassinate Kim Jong-nam in Macau in 2011 but failed.

Afterwards he sent a letter to Jong-un saying "Please spare me and my family", according to Kim Byung-Kee, a member of the South Korean parliamentary intelligence committee, speaking at a press briefing.

He added: "It also said 'We have nowhere to go... we know that the only way to escape is suicide'."

In 2014 Kim Jong-nam, who hit the headlines for his gambling and playboy lifestyle, was seen eating spaghetti bolognese at an Italian restaurant in Jakarta, the capital of Indonesia.

His cousin, Lee Han-young, who defected to South Korea through Switzerland in 1982, was shot and killed by North Korean agents in Seoul in 1997, according to South Korea sources.

According to a book called My Father, Kim Jong Il, and Me by Japanese journalist Yoji Gomi, Kim Jong-Nam reportedly called the current regime "a joke to the outside world".

He added: "Without reforms, North Korea will collapse, and when such changes take place, the regime will collapse."

He is also quoted as saying: "My father was keeping highly secret the fact that he was living with my mother who was married, a famous movie actress, so I couldn't get out of the house or make friends.

"That solitude from childhood may have made me what I am now, preferring freedom."

Jong-Nam is known to have been a computer enthusiast, a fluent Japanese speaker and a student in both Russia and Switzerland. He lived in the capital Pyongyang after finishing his studies and oversaw North Korea's information technology policy.

In May 2001, Kim was arrested on arrival at Japan's Narita International Airport accompanied by two women and a four-year-old boy identified as his son.